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Synergy Motion Analysis System

post #1 of 22
Thread Starter 
I have previously heard and read about the Synergy system. Now that David M has joined our discussions I thought we might be able to specifically talk about it. To start things off I will pose 1 broad question but I have many more.

It seems to me that the Synergy system has great potential. However, as of yet, it does not have any specific/objective validation (at least to my knowledge). Of course there are individual testimonials and those are of some value. The question I have is whether it's greatest potential is in scientific validation of alignment and teaching techniques or as a direct/individual system for alignment and skier improvement.

I would be very interested to see an evaluation of some high level skiers who have had top notch bootfitting, footbeds, alignemnt and coaching and see how they come out based on the synergy analysis. Is it possible that with proper choice of boot, foot position within the boot, alignment, and technique that the role of a system like Synergy's becomes one of conformation?

Perhaps we need this type of techology to optimize performance. Better yet, from my point of view, would be for this type of analysis to assist in validating (or invalidating) the various boot technologies, fitting, alignment, and techique approaches so that as a skier I know whom (or what do-it-yourself appraoches) to trust. It seems to me that at least for those who may not be able to afford this kind of analysis this would allow them to still benefit from its findings and advancements.

[ November 25, 2002, 09:20 AM: Message edited by: Si ]
post #2 of 22
Si, you may not be up to speed on the research I did in 1991. The objective of this work was to validate a hypothetical physiologic model of the ideal skier. In fact we did precisely that. In this project we employed scientists with impeccable credentials.

The issue that seems to have escaped everyone is how does the skier connect to the ground (snow) through the interface presented between the ground and the skier by the stack of equipment. This is by no means a given. It is the first thing the industry, including the Ski Pros, have to come to terms with.

Ground as it relates to GRF is so fundamental to the generation of postural reponses and movement that there is no point in talking of teaching skiing if one does not understand this issue and knows how to make it happen. And neither can one can posture that their position is 'founded in science'. Those who believe otherwise are severely delusional.

The techology synergy used is a thoroughly estbalished and sophisticated science. It confirmed what the eye can not; whether the skier's balance system has successfully negotiated a balance solution with the ground.

Now would a Ski Pro like to explain how the skier connects to the ground?? I am all ears.
post #3 of 22
>... Si, you may not be up to speed on the research I did in 1991. The objective of this work was to validate a hypothetical physiologic model of the ideal skier. In fact we did precisely that. In this project we employed scientists with impeccable credentials. ...

Was this work ever published? If so, where, and was it in a mainstream, peer-reviewed journal?

Unfortunately, a quick medline and google search using keywords like "synergy", "ski", "(posture OR postural)" turned up too large a number of hits to wade through. If I knew the authors, it would help.

Tom / PM
post #4 of 22
Physics man. No like a lot of research it was proprietary. It was intended to provide the basis for product development. And the work was not done by synergy. It was done by another company using personel from the Hugh MacMillan Rehabilitation Center in Toronto, Canada.

This aside the fundamental issue on which the research was predicated is valid: A stable source of ground reaction force is fundamental to human postural responses and movement in terms of locomotion. Unless Newton was wrong reaction must be equal to or greater than action. Normally GRF is much greater than the action force.

Here I can find no basis in current ski knowledge to support this objective.
post #5 of 22
I understand - A lot of what I have done since I entered the commercial sector can't be immediately published because it shoots us in the foot with respect to future patents. I asked only because if your work had been published, it makes finding the work a lot easier for everyone, and it almost always adds the "blessing" of general acceptance.

Be that as it may, do you have any materials on line, a website, etc?

Tom / PM
post #6 of 22
Physics man. I have quite a few patents but they won't have figures. Would you like some references?
post #7 of 22
Physics man. I have quite a few patents but they won't have figures. Would you like some references?
post #8 of 22
Didn't I see a similar system used to make foot beds in Vail? Probes contact the bottom of the foot and digitize it.
post #9 of 22
>... Would you like some references? ...

Absolutely. Just give me the patent #'s and I'll read over them on-line. Thanks.

Tom / PM
post #10 of 22
Thread Starter 
Tom,

Are you going to Whistler for the NIPS conference? It would be a great place to discuss this further. Send me an email and let me know.
post #11 of 22
Si -

Unfortunately, it looks like I can't make it again this year either. This, of course, has absolutely nothing to do with the snow situation in the PNW ... Really! I swear!

Since it sounds like you are definitely going, have lots of fun. We'll all be wishing for snow for you guys.

Tom / PM
post #12 of 22
Quote:
Originally posted by PhysicsMan:
>... Would you like some references? ...

Absolutely. Just give me the patent #'s and I'll read over them on-line. Thanks.

Tom / PM
Send me a private message first. Thanks.
post #13 of 22
David M I have not had time to read through all of the discussions on balance so I could be a bit off. I assume that GRF is Ground Raction Force.

I can understand why GRF would be very difficult to put into any model. There is much information out there on human physiology and movment also the equipment is fairly predictable. These models would be available off the shelf. The interface between skier equipment and snow would be the link that would have little information available and would need to be created.

I absolutely agree with you that an instructor who does not understand GRF is doomed to mediocrity. We all know that humans are use to ground under their feet and sufficient friction under their feet to move in any direction by pushing against that ground. When humans are put onto a surface, such as glare ice, their movements become extremely restricted because they are not use to moving by other physiological means.

Skis on edge develope great friction laterally from side to side but offer little friction longitudinally front to back. When on skis we humans can use our intuitive natural movements from side to side but not front to back. We are also faced with the need to blend our natural side to side movements with our learned front to back movements.

What does all of this mean to the instructor? Simply telling a student to get out of the back seat is not going to cut the mustard. Neither can we show them the correct movements statically from a traverse across the hill when our dynamic front to back movements not present.

In a static position we are all able to flex our ankles and get over the sweet spot of the ski by pushing on the snow. Lotta good that does a student. The minute we start to move, we can no longer push on the ski to flex our ankles but instead, must dorsiflex to achieve the same thing. That is not apparent to any skier without explanation. In addition, one cannot dorsiflex the ankle on skis unless one has planed ahead and allowed gravity to moved the center of mass over the sweet spot and in the direction of the turn.
Neither of those two things are intuitively apparent to a student nor can they be shown from a static position. You need to present those two ideas in enough different ways so the light bulb goes off. There are also exercises that set the student up for success.

Fore and Aft alignment are also important for the student to be able to dorsiflex the ankles. Too far back and all bets are off. Too far forward same thing.
post #14 of 22
Quote:
Originally posted by Pierre:

Neither of those two things are intuitively apparent to a student nor can they be shown from a static position. You need to present those two ideas in enough different ways so the light bulb goes off. There are also exercises that set the student up for success.
Thanks for the synopsis of your understanding of the role of the foot in fore/aft balance. The related thread had got me a litle lost, Pierre. A lightbulb has gone off.

Nettie
post #15 of 22
Pierre,

Try the reverse traverse. While going backwards in a traverse watch how fast people will lean forward. (don't look down) If you remind them to feel where they are, usually they will be able to remember where they were, when going forward again. Great way to find the sweet spot.
post #16 of 22
Like doing a falling leaf! [img]smile.gif[/img]
post #17 of 22
Pierre: David M I have not had time to read through all of the discussions on balance so I could be a bit off. I assume that GRF is Ground Reaction Force.

The interface between skier equipment and snow would be the link that would have little information available and would need to be created.

DM: There are a few issues here:
1. When a ski is on edge where is the ‘ground’ in relation to the skier’s foot? Is it under the portion of the ski edge directly under foot?
2. Where is the center of the force applied to the ground by the skier’s foot against ground reaction force?
3. Are the opposing forces aligned? If so, by what mechanism? If not what will happen?
post #18 of 22
David, see what I mean? I'm desperatly trying to follow you in these discussions and since personality remarks have gone , hopefully, I get some nuggets here and there, but...

In the answer to Pierre you pose three questions and you give no answers, or least your position of what is correct.

Why those cliffhangers?

...Ott
post #19 of 22
Ott I don't think David M is picking on me at all or trying to test me in this case. What he is asking is very legitimate and very complex questions. I do the same kind thing sometimes. I will pose something in the form of a question when what I really want is some tidbit of information that will jog my own brain into gear. The questions were.

Quote:
1. When a ski is on edge where is the ‘ground’ in relation to the skier’s foot? Is it under the portion of the ski edge directly under foot?
2. Where is the center of the force applied to the ground by the skier’s foot against ground reaction force?
3. Are the opposing forces aligned? If so, by what mechanism? If not what will happen?
Please cut me some slack, I don't expect everyone to follow this. I can at time go way off the scale.

In answer to question one and three.I would say that cetrifugal force is through the center of the foot and centripital force is somewhere along the collect edge. Lever/fulcrum mathematics. I would expect the two forces to be offset some. The problem lay in the fact that the offset is constantly changing as apparent deck angle changes. This is somewhat simplified by the fact that the only interface is the ski snow interaction with the possible exception of pole plant.

Question 2 is a bit tougher as what we really have is a vector addition between centrifugal force and acceleration/deceleration/gravity/slope acting along the collective edge of the ski. In a practical sense, this is handled by progressively leveraging the front and back of the ski throughout the turn. Since it is a dynamic force it would be very hard to mathematically simulate. Simulating park and ride railroad turn forces would be much easier.

My guess David is that you did not have the kind of budget that this kind of simulation would have required to do a decent job. In other words, I doubt the US military funded you. Did you get close enough to get useful information for use in product development. I would doubt it, but your understanding is probably much much greater. :
post #20 of 22
Pierre, I wasn't thinking about you or that David was picking on you, I just wanted the answers to these questions in the same post for my sake.

Why it is so easy for me to understand Bob Barnes' posts is that he doesn't let me hang there, except for one case of 'ski the slow line fast' which I also didn't appreciate since he gave clues but never really answered, luckily I have his book and can read up on it.

Also nolo, who often quotes some author or other at least puts the relevant quotes in her posts rather than make me go and get the book to look it up.

And forgive me, but your answer to David's question leave me, and I'm sure many other forum members, baffled to the point of saying "so what?". These things happen so why do I have to think about them.

How do you give that knowledge to your class this evening? Does it matter to them? I don't think so, I think this is for the personal interest of instructors who care about the minutia of boot fitting, and I know you are one of them.

Were you out at BM/BW yesterday? Ann and I are going tomorrow or Friday. I just hate to ski through those snow machine blasts which will be going day and night. See you on the hill.

...Ott
post #21 of 22
Ott: The real answers to the questions that David posted cannot really be answered to any absolutes and have nothing to do with teaching students. I doubt David has real answers for those questions. Mathematical simulators are very complex and require some things that are truely dynmaic to be represented as fixed static numbers. Therefore the model is not exact and there is no defintive answer to the questions. There are perhaps a dozen people on this forum who would be able to follow those questions and answers. That is why I said don't slap me for going off the scale. I am just one of those people who are comfortable with abstract solutions and answers as well as real solutions and answers.
His questions are the same as "Did the Chicken come before or after the egg?" [img]smile.gif[/img]

[ December 04, 2002, 10:17 AM: Message edited by: Pierre ]
post #22 of 22
When it comes to counter pressures, The only thing we can use is our center of gravity, and our mass. Time can influence the magnitude, but not the direction.

CalG
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